Nope. The only possible places for an on-screen Refit Dreadnought would be the monitors in Treks I-III, or as a member of the Frankenstein fleets in Deep Space Nine. Both of those have been documented and described in such detail that I don't think something as recognizable as a dreadnought could've slipped through the cracks.

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“I come here to have fun and fuck around merrily. I expect to showered by all kind of random crap.”
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